Verification Trials of 5G Communications in High-speed
Mobile Environments

Masanori Ichinose

DirectorSolution Services
NTT Communications Corporation

1. Introduction
The Fifth Generation Mobile Communications System (5G)
will provide across-the-board enhancements—unrivaled capacity,
ultra-high speed, multiple simultaneous connections, ultra-reliable
and low latency—and should lead to early implementation of an
ICT infrastructure supporting the IoT era and sustained growthof Japan’s economy for years to come. With a planned rollout of5G slated for 2020, R&D supporting 5G wireless access and othertechnologies, and Field Trials for new 5G services are well underway.
This article provides an overview of Field Trials recently
conducted by NT T Communications (NT T Com) incollaboration with NTT DOCOMO to assess technical andoperating conditions of a 5G mobile communication systemcapable of supporting high-speed 2Gb/s Gbps throughput for
high-speed public transportation. The system is designed toprovide entertainment for passengers when traveling on fastmoving trains and motor vehicles.

2. 5G wireless transmission characteristics inhigh-speed mobile environments exceeding
90 km/hTwo trials were conducted to assess the transmission
performance of 5G wireless access for motor vehicles (cars andbusses) running on highways and for conventional trains operating

Ichiro Nakagawa

Senior ManagerSolution Services
NTT Communications Corporationat high speed: the vehicle transmission trials were carried out
at Fuji Speedway while the railway transmission trials wereconducted on the Tobu Railway Nikko Line.
2.1 Vehicle transmission trials at Fuji Speedway
The vehicle trials were conducted on February 7-9, 2018 atFuji Speedway (in Shizuoka Prefecture) by constructing a 5G
transmission zone near the grand stand and transmitting 5G
wireless content to vehicles driving around the track at high speed(Figure 1).
The base station was set up near the grandstand along thehome straight with a 45° angle of orientation to the course, andthe mobile station was mounted on the roof of the test vehicles.
Specifications of the transmitter were as follows: center frequencyof 27.875 GHz, bandwidth of 700 MHz, and number of antenna
elements (base station: 96, mobile station: 64). Through thesetrials, we were able to verify a maximum throughput of 2.24 Gbps
at vehicle speeds above 90 km/h.
2.2 Train transmission trials on Tobu Railway Nikko LineThe train trials were done in collaboration with Tobu Railway
on February 19-23, 2018. For the purpose of these trials, 5Gtransmission zones was deployed near Ienaka Station and Niregi
Station along the Tobu Nikko Line, and 5G wireless content
was transmitted to the Sky Tree Train, EMU 634 (a sightseeing■ Figure 1: Wireless transmission trials for high-speed vehicles at Fuji Speedway

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■ Figure 2: Wireless transmission trials for high-speed trains on Tobu Railway Nikko Line■ Figure 3: Overview of entertainment delivery trial

train operated by Tobu Railways) that was traveling at high speed(Figure 2).
The equipment was set up so we could assess handover
performance of 5G transmissions: the base stations were under
the control of the core network near Ienaka Station, with basestation base band unit 1 deployed at the north end of the platform
and base station base band unit 2 set up in a vacant lot southof the station. Two antenna units were connected to each basestation base band unit to provide transmission diversity. Theantenna was attached to the mobile station in such a way that itwas visible through the front windshield of the train crew cabin.
Specifications of the transmitting equipment were as follows:
center frequency of 27.875 GHz, bandwidth of 700 MHz, andnumber of antenna elements (base station: 96, mobile station: 64).
Based on the trials, we were able to verify a maximum throughput
of 2.08 Gbps when the train was moving at a speed of 90 km/h.
We also confirmed that the handover occurred seamlessly without
issue.
The two antenna units subordinate to the base stationbase band unit installed near Niregi Station were deployed ina distributed configuration. Specifications of the transmitting
equipment were as follows: center frequency of 27.900 GHz,
bandwidth of 730.5 MHz, and number of antenna elements(base station: 128 × 2 unit, mobile station: 8). To make sure themobile station was within direct line-of-sight of the base stationtransmission point inside the train car, the antenna was mounted
on the front windshield in front of the driver’s seat shieldedby a sheet of clear acrylic. Here again we verified a maximum
throughput of 2.90 Gbps when the train was traveling at 90 km/h.

3. Entertainment field trials
Riding long distances on public transportation can takeconsiderable time, and this of course increases the demand for everfaster travel speeds. Providing passengers with entertainment in
the form of high-definition video services while traveling is also
exceedingly important, for it helps passengers pass the time whilein transit. These considerations led us to carry out these trials totest and evaluate 5G high-definition video services for passengers
riding on trains and busses and taxies operated by passenger
automobile transport businesses at speeds in excess of 90 km/h(Figure 3).
We might assume that the most basic 5G services soughtby train and car service passengers will be Internet connectivity
services. But the goal of these trials was to assess and visualize
services that exploit 5G capabilities, so we focused on highdefinition video services for passengers traveling at high speed
on various modes of public transportation. Compared to legacytransmission services, delivering high-definition video topassengers in trains and vehicles offers significant advantages,
most notably the very high capacity of 5G transmission. We canNew Breeze Autumn 20187■ Figure 4: Hybrid video distribution service

high-speed communication in the 28-GHz band for vehicles andanticipate that this larger capacity will provide sharper higher
trains moving at 90 km/h. In the vehicle transmission trials at
definition video, a greater range of channels, and instantaneous
Fuji Speedway and the train transmission trials on Tobu Railway
live feeds and other information delivery services.
Nikko Line we demonstrated that very high throughputs in excess
There are two types of video distribution services—linearof 2 Gbps were feasible at speeds of 90 km/h.
distribution (program organization) services and on-demandThis abilit y to deliver ver y-high-speed Gbps-class
distribution services—but for these trials we deployed very few
communications in high-speed mobile environments will open
base stations and the communication time was exceedingly
the way to many new 5G entertainment services tailored for public
limited. So for our purposes, we adopted a hybrid compromisetransportation including the delivery of breaking news clips of thetype distribution service so we could assess both the instantaneous
2020 Tokyo Olympics and Paralympic Games to passengers whilenature of the linear distribution service, and the convenience of thetravelling on Japan’s high-speed trains.
on-demand distribution service (Figure 4).
We installed a video distribution server (master server) on
the base station side and a cache server between passenger user
terminals inside the train, then split the network into
■ Figure 5: H igh-definition video trials for high-speed trains on Tobu
two sub-networks: an inter-server network between
Railway Nikko Linethe master server and the cache server, and an enduser network between the cache server and the user
terminals. With this architecture, even if the cache server
cannot exploit G5 communication to add and update
content added or updated on the master server by thecarrier, content on the cache server can be appropriately
updated later using 5G communications to deliver almost
instantaneous services very similar to live streaming tousers.
Using this system, we conducted trials on February
19-23, 2018 by downloading multiple 4K/8K video
files within the 5G transmission zone near Ienaka
Station on the Tobu Railway (Figure 5). During the21 seconds it took for the train to pass through the5G transmission zone, a total of 1.2 GB of 4K/8K
video data was transmitted over the system which wereshown on a 4K display and on a 17-inch 8K display set
up in the train for the experiment. By providing veryhigh-speed Gbps-class communications in high-speed
mobile environments, this will make it possible to deliver
breaking news and other high-definition video clips in atimely manner to passengers riding on high-speed trains.

4. Conclusions
In these trials we evaluated the performance of 5G

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